Breech mechanism including self-aligning breech blocks

ABSTRACT

A molding machine of the type comprising tie rods mounted to one platen which are received by breech mechanisms associated with a second platen. Each breech mechanism comprises a plurality of cooperative breech blocks driven towards-and-away from one another by individual cylinder-and-piston actuators which exert equal, oppositely directed moving forces on the breech blocks. The breech blocks are mounted for lateral and longitudinal movement relative to their respective tie rods, thereby enabling the breech blocks to be self-aligning with the tie rods and accommodating tie rod stretch.

United States Patent Farrell Apr. 2, 1974 [54] BREECH MECHANISM INCLUDING 3,669,599 6/1972 Snider et al 425/242 SELF-ALIGNING BREEC" K FORElGN PATENTS OR APPLICATIONS [75] Inventor: Robert E. Farrell, Nashua, NH. 888,184 1/1962 Great Britain 425/242 73 A, I d M h I N h l l ssgnee g ac may no as ua Primary Examiner-R. Spencer Annear Attorney, Agent, or Firm-Robert R. Paquin; David [22] Filed: Apr. 21, 1972 W. Tibbott Appl. No.: 246,418

[52] U.S. Cl 425/450, 74/527, 425/242, l64/34l [51] Int. Cl. B29f l/00,-G05g 5/06 [58] Field of Search 425/149, 150,242, 450; 74/527; 164/341 [56] References Cited UNITED STATES PATENTS 2,862,238 12/1958 Cuzzi 425/450 3,465,387 9/1969 Allard et aL. 425/149 3,505,708 4/1970 Moslo 425/242 X 3,590,418 7/1971 Hoeschel 425/242 3,656,877 4/1972 Aoki 425/242 X [57] ABSTRACT A molding machine of the type comprising tie rods mounted to one platen which are received by breech mechanisms associated with a second platen. Each breech mechanism comprises a plurality of cooperative breech blocks driven towards-and-away from one another by individual cylinder-and-piston actuators which exert equal, oppositely directed moving forces on the breech blocks. The breech blocks are mounted for lateral and longitudinal movement relative to their respective tie rods, thereby enabling the breech blocks to be self-aligning with the tie rods and accommodating tie rod stretch.

14 Claims, 5 Drawing Figures SHEEI 1 [IF 2 PATENTEBAFR 2 I974 72 FIG. 3

1 BREECH MECHANISM INCLUDING SELF-ALIGNING BREECH BLOCKS The present invention relates to molding machines including tie rods gripped by breech mechanisms during the machine operation and more particularly to the provision of a new and improved breech mechanism for a molding machine of this type.

Conventionally, a breech mechanism of such a molding machine generally has included a plurality of breech blocks, cooperative to grip a therebetween tie rod, which are driven towards-and-away from one another by actuating means in the form of a single cylinder-and-piston actuator or other similar driving means producing unbalanced reactionforces when the breech blocks engage a tie rod. conventionally, also, the breech blocks frequently have not been both self alignable with the received tie rod and capable of accommodating tie rod stretch.

An object of the present invention is to provide a new and improved breech mechanism for a molding machine, which breech mechanism is particularly constructed and arranged to minimize the reaction effects arising when the breech blocks engage a tie rod.

Another object is to provide a new and improved breech mechanism for molding machine, which breech mechanism is particularly constructed and arranged such that equal and opposite moving forces are exerted on the breech blocks.

Another object is to provide a new and improved breech mechanism for a molding machine, which breech mechanism is particularly constructed and arranged to enable the breech blocks to be both readily self-alignable with the received tie rod and also capable of accommodating tie rod stretch.

Other objects and advantages of the invention will be apparent from the following description taken in connection with the accompanying drawings wherein, as will be understood, the preferred form of the invention has been given by way of illustration only.

In accordance with the invention, a molding machine may comprise a first platen, a second platen movable towards-and-away from the first platen, at least one tie rod mounted to one of the platens longitudinally projecting from such platen towards the other thereof, a breech mechanism associated with said other platen for gripping the tie rod, the breech mechanism including a plurality of breech blocks cooperative to grip a therebetween tie rod and moveable towards-and-away from one another, actuating means for moving each of the breech blocks towards-and-away from the other, and such actuating means comprising an individual pressure fluid operative cylinder-and-piston actuator for each of the breech blocks. Also, in accordance with the invention, each breech block may be mounted for movement both laterally and longitudinally of the tie rod by a mounting means comprising support means, shoe means movably on the support means, and carriage means connected to the breech block and movably mounted on the support means by the shoe means.

Referring to the drawings:

FIG. 1 is an elevational view, partially broken away and in section, of an injection molding machine including a plurality of breech mechanisms constructed in accordance with one embodiment of the invention;

FIG. 2 is an enlarged, perspective view illustrating one of the breech mechanisms of the injection molding machine shown in FIG. 1;

FIG. 3 is a perspective view illustrating one of the shoes supporting the breech blocks of the breech mechanism shown in FIG. 2;

FIG. 4 is a view schematically illustrating the supply of pressure fluid to the cylinder-and-piston actuators for the breech blocks of such breech mechanism; and

FIG. 5 is a view schematically illustrating the breech mechanism shown in FIG. 2.

Referring more particularly to the drawings wherein similar reference characters designate corresponding parts throughout the several views, FIG. 1 illustrates the breech mechanism of the invention as applied to a molding machine of the type described in US. Pat. No. 3,590,418, issued July 6, 1971 and assigned to the assignee of the present invention. It will be understood, however, that the invention has been shown and described as applied to such machine only for the purposes of illustration; and the invention is equally applicable to other forms of molding machines of the beforedescribed general type.

The molding machine illustrated in FIG. 1 comprises a generally vertical first platen 10 mounted upon the upper surface of a ground supported base or base pad 12 which also carries the injection unit of the molding machine, such injection unit being designated generally as 14. The injection unit 14 may be of any suitable conventional construction and, as shown, includes a receiving hopper 16, an injection ram device 18, a plasticizing and feed device 20, and a discharge nozzle 22 which projects through an opening through the first platen 10. A generally vertical second platen 24, oppositely disposed to the first platen 10, is suspended by a supportingshoe 26 from a generally horizontal guide track 28 which is, in turn, ground mounted by a plurality of supporting posts 30. The platens 10,24 carry the usual mating mold sections or halves 32,34; and the 2 second platen 24 is, during the operation of the machine, driven by a cylinder-and-piston motor 36 towards-and-away from the firstplaten 10 between a mold closed-position (shown'in solid lines in FIG. 1)

and a mold fully open position (shown in broken lines in FIG. 1).

The second platen 24 carries four tie rods 38 which project horizontally from the second platen 24 towards the first platen l0 and, with the second platen 24 in its mold closed position, slidably extend through openings in the first platen 10 into individual breech mechanisms, each designated generally as 40, associated with the latter. The tie rods 38, as illustrated, extend through the second platen 24 into individual retraction tubes 42 mounted on the second platen 24 and are in the manner described in US. Pat. No. 3,465,387, issued Sept. 9, 1969 and assigned to the assignee of the present invention, adjustable by drive means (not shown) on the second platen 24 to vary the portions of their lengths projecting from the second platen 24 towards the first platen 10. Such portions of the lengths of the tie rods 38, as will be understood, are advantageously maintained sufficiently short to permit the tie rods 38 to be entirely removed from their openings in the first platen 10 during the movement of the second platen 24 away from the latter thereby facilitating the a molding machine of this general type, if desired, can

, be obtained from the beforementioned U. S. Pat. No.

3,590,418; and it will be understood that, as disclosed in such patent, the tie rods 38 alternatively could be mounted to the first platen in which event the breech mechanisms 40 would be associated with the second platen 24 for movement therewith.

The breech mechanisms 40 are all of identical construction and arrangement and hence, although only one thereof has been illustrated in FIGS. 2 through 5 and hereinafter specifically described, it will be'understood that all of the other breech mechanisms 40 are the same as that so illustrated and described. The breech mechanisms 40 each include a breech housing or casing 44 containing aligned, upper and lower breech blocks 46,48, respectively, which are vertically movable towards-and-away from one another and provided with semi-circular recesses 50,52 cooperative to grip the end 54 of a tie rod 38 between-the breech blocks 46,48. The semi-circular recesses 50,52 and the tie rod end 54, as illustrated, are preferably provided with cooperative grooves 56,58, respectively, facilitating the gripping of the rod end 54 by the breech blocks 46,48.

As illustrated in FIG,'2, the breech blocks 46,48 are mounted in a manner permitting their'longitudinal and lateral movement relative toa therebetween tie rod end 54, thus accommodating tie rod stretch and enabling the breech blocks 46,48 to be self-aligning with the tie rod end 54. More particularly, the breech blocks 46,48 are slidably mounted for their beforedescribed vertical movement on a pair of vertical slide rods 60 which at opposite ends areaffixed to carriage frames or carriages 62. The carriages 62, in turn, are each slidably mounted on a pair of horizontal slide rods 64, extend- :ing parallel to the tie rod 38, by separate supporting or which engages a corresponding flat surface 74 on a carriage 62 to key the latter to the bearing shoe 66. Hence, the carriages 62 are resultantly slidable both longitudinally along and laterally of the horizontal tie rods 62; and the breech blocks 46,48, being carried by the carriages 62 through the vertical slide rods 60, are enabled to both move longitudinally of the tie rod 38 to accommodate tie rod expansion and horizontally laterally of the tie rod 38 to readily self-align therewith.

The breech blocks 46,48 are vertically driven towards-and-away from each other by individual cylinder-and-piston actuators 76 carried by the carriages 62 whereby the actuators 76 for the breech blocks 46,48 are on opposite sides of the latter. The actuators 76 are of identical construction and size and each include a cylinder 78 fixedly mounted on a carriage 62 and a piston 80 which is slidably in the cylinder 78 and connected to a breech block 46 or 48 by an extension rod 82. Both of the actuators 76 of each breech mechanism 40 are connected to a common source of pressure fluid whereby the fluid at such common pressure is supplied to their cylinders 78 to drive the breech blocks 46,48 towards one another. More specifically, as schematically depicted in FIG. 4, the pressure fluid is supplied through a singly supply conduit 84, communicating with a source (not shown) of the pressure fluid, and branch conduits 86,88 connecting the head ends of the cylinders 78 of both actuators 76 to such supply conduit 84. As a result of the before-described construction and arrangement, the reaction forces produced in each breech mechanism 40 upon engagement of the breech blocks 46,48 with a therebetween tie rod end 54 are equal and opposite. Hence, these reaction forces cancel each other within the assembly formed by the carriages 62 and the breech blocks 46,48; and the reaction forces produced between such assembly and the horizontal slide rods 64 is only equal to the weight of the assembly. Also, as the head ends of the cylinders 78 of the actuators 76 are connected to receive pressure fluid from a common supply conduit 84, full gripping pressure on the tie rod end 54 can only occur after both breech blocks 46,48 engage the end 54; and, as the gripping forces of the breech blocks 46,48 on the tie rod end 54 are equal and opposite, such gripping does not in any manner tend to move the tie rod 38 or to cause an undesirable net reaction therein.

The rod ends of the cylinders 78 of the actuators 76 are provided with' individual fluid connections which communicate with the source.(not shown) of the pressure fluid in a conventional manner; and suitable conventional valving means (not shown) interconnect the fluid connections 90 and the supply conduit 84 whereby, in the conventional manner, pressure fluid may be selectively supplied through each thereof to one end of each of the cylinders 76 while fluid is ex-' hausted through the other thereof from the other end of each cylinder 76.

Each breech mechanism is provided with the usual load cell 92 which, after the tie rod ends 54 have been gripped by the breech blocks 46,48 of all of the breech mechanisms 40, is the usual manner fluid actuated to exert clamping force on the second platen 24 through the respective adjacent breech blocks 46,48 and their gripped tie rod 38. In addition, as illustrated, each breech mechanism 40 is provided with a cylinder 96, aligned with its respective tie rod 38, which slidably contains both a cushioning piston 98 and a theresurrounding break-away or push-back piston 100. The cushioning piston 98, as will be understood, is fluid biased to engage the tie rod end 54 during axial movement of the tie rod 38 into the breech mechanism 40, thereby cushioning or absorbing the shock of such tie rod movement. The push-back piston 100 is fluid actuated to, in cooperation with the cushioning piston 98, assist in initiating axial movement of the tie rod 38 out of the breech mechanism 40 after opening of the breech blocks 46,48 by their movement from one another. Load cells and cushioning and push-back cylinder and-piston arrangements of this general type are, of course, per se well known in the art. For example, the beforementioned U.S. Pat. No. 3,465,387 described generally similar apparatus for these purposes.

The operation of the before described molding machine is believed to be apparent from the preceeding description. However, in order to insure understanding of the breech mechanisms 40, a brief description of their operation is hereinafter given.

During the driven movement of the second platen 24 towards its mold closed position, the tie rod ends 54 are moved intermediate the open breech blocks 46,48 of their respective breech mechanisms 40, while low pressure fluid in the cylinders 96 causes the cushioning cylinders 98 to cushion the tie rod movement. Each tie rod end 54 during its said movement trips the usual limit switch 102 whereupon, afterall such limit switches 102 have been so tripped indicating that the tie rod ends 54 are all in position for gripping by their respective breech blocks 46,48, pressure fluid is caused to flow from the source (not shown) through the supply conduits 84 and branch conduits 86,88 to the head ends of the cylinders 78. Simultaneously, pressure fluid is exhausted from the rod ends of the cylinders 78; and, hence, the breech blocks 46,48 of each breech mechanism 40 are vertically driven towards one another to closed positions wherein they cooperate to grip the therebetween tie rod end 54 and then apply full clamping force to the latter. The breech blocks 46,48 during their said driven movement, automatically move laterally as necessary for their self-alignment with the tie rod ends 54 and also longitudinally of the tie rods 38 as necessary to compensate for tie rod stretch.

During the movement of the breech blocks 46,48 to their closed positions, the limit switch 104 is resultantly tripped, thereby causing pressure fluid to be supplied through the passage 106 to the load cell 92. This pressure fluid in the conventional manner causes the load cell 92 to apply clamping force on the second platen 24 through the breech blocks 46,48 and the tie rods 38; and during the application of such clamping force, plasticized material is injected between the mold halves 32,34. Then, after a predetermined time period preset into the usual timer, the passage 106 is connected to exhaust, thereby releasing the clamping pressure; and pressure fluid is supplied to the rod ends of the actuator cylinders 78, while fluid is exhausted from the head ends thereof, thereby driving the breech blocks 46,48 one from the other to their open positions. Thereupon, the limit switch 108 is tripped causing the pistons 98,100 to be fluid driven to initiate movement of the tie rods 38 out of the breech mechanisms 40 and the second platen 24 is driven away from the first platen preparatory to commencing another operating cycle of the machine.

From the preceding description it will be seen that the invention provides new and improved means for accomplishing all of the aforestated objects and advances. It will be understood, however, that, although only a single embodiment has been illustrated and herein beforedescribed, the invention is not limited merely to this such single embodiment, but rather contemplates other embodiments and variations within the scope of the following claims.

Having thus described my invention, 1 claim:

1. In a molding machine, a first platen, a second platen movable towards-and-away from said first platen, at least one tie rod mounted to one of said platens longitudinally projecting from said one platen towards the other thereof, a breech mechanism asso ciated with said other platen for gripping said tie rod, said breech mechanism including a purality of breech blocks cooperative to grip a therebetween tie rod and movable towards-and-away from one another, actuating means for moving each of said breech blocks towards-and-away from the other, said actuating means comprising individual pressure fluid operated cylinderand-piston actuators for each of said breech blocks, means mounting said breech blocks for movement longitudinally of said tie rod and also laterally of said tie rod to permit self-alignment of said breech blocks with a therebetween tie rod during movement of the breech blocks towards one another, said mounting means for each said breech block including rod means on the opposite side of said other platen from said one platen and extending longitudinally of said tie rod, carriage means connected to the breech block, and shoe means mounting said carriage means on said rod means for both longitudinal and lateral movement thereon.

2. A molding machine according to claim 1, wherein said cylinder-and-piston actuators are constructed to cause equal oppositely directed moving forces to be exerted on said breech blocks.

3. A molding machine according to claim 1, wherein said cylinder-and-piston actuators are'on opposite sides of said breech blocks.

4. A molding machine according to claim 1, further comprising supply means for supplying pressure fluid at common pressure to said cylinder-and-piston actuators.

5. A molding machine according to claim 4, wherein said supply means comprises a supply conduit communicating with a source of the pressure fluid, and branch conduits connecting said supply conduit with said cylinder-and-piston actuators.

6. A molding machine according to claim 1, wherein said cylinder-and-piston actuators are constructed to cause pressure fluid at common pressure to exert equal, oppositely directed forces on said breech blocks during their movement towards one another, and further comprising supply means for supplying fluid at common pressure to said cylinder-and-pressure actuators to so move said breech blocks.

7. A molding machine according to claim 6, wherein said supply means comprises a supply conduit communicating with a source of pressure fluid and branch conduits connecting said supply conduit with said cylinderand-piston actuators.

8. A molding machine according to claim 1, wherein each said shoe means comprises arcuatebearing surface means slidably engaging a saidlrod means and also keying surface means keying said carriage means to the shoe means.

9. A molding machine according to claim 1, wherein each said rod means comprises a plurality of horizontal slide rods, each said shoe means comprises a plurality of shoe members each having an arcuate bearing surface slidably on one of said slide rods and also a keying surface keying a said carriage means to the shoe mem ber, and further comprising vertical slide rod means mounting said breech blocks to said carriage means.

10. A molding machine according to claim 9, wherein the said keying surface of each said shoe member is bounded adjacent opposite ends of the shoe member by retaining portions of the latter.

11. In a molding machine, a first platen, a second platen movable towards-and-away from said first platen, at least one tie rod mounted to one of said platens longitudinally projecting from said one platen towards the other thereof, a breech mechanism associated with said other platen for gripping said tie rod, said breech mechanism including a plurality of breech blocks cooperative to grip a therebetween tie rod and wherein each said mounting means further comprises shoe means mounting the carriage means on the rod means for movement thereon.

13. A molding machine according to claim 12, wherein said shoe means is separate from both said carriage means and said rod means.

14. A molding machine according to claim 13, wherein each said rod means comprises a plurality of horizontal slide rods, each said shoe means comprises a corresponding plurality of shoe members each having an arcuate bearing surface slidably on one of said slide rods and also a keying surface keying a said carriage means to the shoe member, and further comprising vertical slide rod means mounting said breech blocks to said carriage means. 

1. In a molding machine, a first platen, a second platen movable towards-and-away from said first platen, at least one tie rod mounted to one of said platens longitudinally projecting from said one platen towards the other thereof, a breech mechanism associated with said other platen for gripping said tie rod, said breech mechanism including a purality of breech blocks cooperative to grip a therebetween tie rod and movable towardsand-away from one another, actuating means for moving each of said breech blocks towards-and-away from the other, said actuating means comprising individual pressure fluid operated cylinder-and-piston actuators for each of said breech blocks, means mounting said breech blocks for movement longitudinally of said tie rod and also laterally of said tie rod to permit selfalignment of said breech blocks with a therebetween tie rod during movement of the breech blocks towards one another, said mounting means for each said breech block including rod means on the opposite side of said other platen from said one platen and extending longitudinally of said tie rod, carriage means connected to the breech block, and shoe means mounting said carriage means on said rod means for both longitudinal and lateral movement thereon.
 2. A molding machine according to claim 1, wherein said cylinder-and-piston actuators are constructed to cause equal oppositely directed moving forces to be exerted on said breech blocks.
 3. A molding machine according to claim 1, wherein said cylinder-and-piston actuators are on opposite sides of said breech blocks.
 4. A molding machine according to claim 1, further comprising supply means for supplying pressure fluid at common pressure to said cylinder-and-piston actuators.
 5. A molding machine according to claim 4, wherein said supply means comprises a supply conduit communicating with a source of the pressure fluid, and branch conduits connecting said supply conduit with said cylinder-and-piston actuators.
 6. A molding machine according to claim 1, wherein said cylinder-and-piston actuators are constructed to cause pressure fluid at common pressure to exert equal, oppositely directed forces on said breech blocks during their movement towards one another, and further comprising supply means for supplying fluid at common pressure to said cylinder-and-pressure actuators to sO move said breech blocks.
 7. A molding machine according to claim 6, wherein said supply means comprises a supply conduit communicating with a source of pressure fluid and branch conduits connecting said supply conduit with said cylinder-and-piston actuators.
 8. A molding machine according to claim 1, wherein each said shoe means comprises arcuate bearing surface means slidably engaging a said rod means and also keying surface means keying said carriage means to the shoe means.
 9. A molding machine according to claim 1, wherein each said rod means comprises a plurality of horizontal slide rods, each said shoe means comprises a plurality of shoe members each having an arcuate bearing surface alidably on one of said slide rods and also a keying surface keying a said carriage means to the shoe member, and further comprising vertical slide rod means mounting said breech blocks to said carriage means.
 10. A molding machine according to claim 9, wherein the said keying surface of each said shoe member is bounded adjacent opposite ends of the shoe member by retaining portions of the latter.
 11. In a molding machine, a first platen, a second platen movable towards-and-away from said first platen, at least one tie rod mounted to one of said platens longitudinally projecting from said one platen towards the other thereof, a breech mechanism associated with said other platen for gripping said tie rod, said breech mechanism including a plurality of breech blocks cooperative to grip a therebetween tie rod and movable towards-and-away from one another, motor means for moving each said breech block towards-and-away from the other, and means mounting said breech blocks for movement both longitudinally and laterally to said tie rod, said mounting means for each said breech block comprising rod means on the opposite side of said other platen from said one platen and extending longitudinally of said tie rod, and carriage means connected to the breech block and mounted on said rod means for both longitudinal and lateral movement thereon.
 12. A molding machine according to claim 11, wherein each said mounting means further comprises shoe means mounting the carriage means on the rod means for movement thereon.
 13. A molding machine according to claim 12, wherein said shoe means is separate from both said carriage means and said rod means.
 14. A molding machine according to claim 13, wherein each said rod means comprises a plurality of horizontal slide rods, each said shoe means comprises a corresponding plurality of shoe members each having an arcuate bearing surface slidably on one of said slide rods and also a keying surface keying a said carriage means to the shoe member, and further comprising vertical slide rod means mounting said breech blocks to said carriage means. 